Wide tunable band filters are used in many applications, such as communication systems and radar systems. Specific applications include RF (radio frequency) and microwave transmitters and receivers, satellite communication systems, communication relays and various measurement systems. Wide tunable band filters are used to pass signals having specific frequencies with minimum insertion loss while rejecting other signals outside the specified frequencies.
The growing use of mobile devices and wireless communication systems has increased the demand for communication components, including wide tunable band filters. Existing wide band filters typically include resonators that have specific resonance frequencies. To perform certain filter characteristics (e.g., filter performance) using single mode resonators, multiple resonators are necessary. Thus, in systems requiring high order filters, the use of multiple single mode resonators increases the complexity of the design as well as the space occupied by the multiple resonator filters.